Rotary brush with special bristle support means



June 27, 1961 v. K. CHARVAT 2,989,767

ROTARY BRUSH WITH SPECIAL BRISTLE SUPPORT MEANS Filed Dec. 3, 1957 INVENTOR. VfR/VO/V K CHARVAT OW v A TTORNLY$ United States Patent 2,989,767 ROTARY BRUSH WITH SPECIAL BRISTLE SUPPORT MEANS Vernon K. Ch'arvat, Bay Village, Ohio, assignor to The Osborn Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Filed Dec. 3, 1957, Ser. No. 700,496 7 Claims. (Cl. 15-198) This invention relates as indicated to a novel rotary brush with special bristle support means, and more particularly to power driven end brushes and the like in which auxiliary support is provided for the bristles where they emerge from the socket, hub, back or the like in which they are secured.

An important category of power driven brushes includes those in which the brush material such as wire bristles, for example, extends generally parallel to the axis of rotation of the tool, brushes of this type ordinarily being designated as end brushes or cup brushes. In Peterson Patent 2,325,629 there is disclosed a form of end brush wherein the generally axially extending bristle material may be encircled and restrained by means of a coiled wire spring, and in Peterson Patent 2,421,647 there is disclosed a form of end brush provided with a removable sleeve to restrain bn'stle movement. Reference may also be had to Benyak Patents 2,449,158 and 2,755,496 for other similar brushes of a type adapted to be modified and improved in accordance with my invention.

Bridles of the type disclosed in such prior patents are of assistance in preventing long Wire breakage which is quite common in end brushes due to flexing and concentration of stress at the points where such'wires emerge from the supporting cup or other socket. It has been found, however, that in the operation of many such brushes it is important to allow the brush bristle material to swing radially outwardly of the axis of rotation under the influence of centrifugal force, and a bridle which merely holds the bundle of bristles together is not entirely satisfactory. Such prior bridles have accordingly not been generally adopted especially when end brushes having fine wire bristles are employed. It has been found better to suffer long fracture of such bristles in use and accordingly rapid deterioration and short life of the tool rather than unduly to restrain the action of the brush material. It is accordingly an important object of my invention to provide means for regulating the action of brush bristle material in use, to damp vibration of the bristles and to reduce localized concentrations of stress tending to cause long fracture thereof.

A further object is to provide an end brush in'which the bristle material, and particularly fine wire bristle material, is'restrained in a yielding manner where it protrudes from the supporting cup or other socket.

Still another object is to provide suitable restraining means adapted to encircle a bundle of brush bristle material with a tight clamping action but which will nevertheless yield sufli'ciently to the movement of the bristles in use to damp vibration of the same and permit the bristles to flare widely outwardly under the action of centrifugal force.

Other'ob'jects of the invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention then'comprises the features hereinafter fully described and particularly pointed out in the claims, the following description andthe annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

2,989,767 Patented June 27-, 1961 ice In said annexed drawing:

FIG. 1 is a shank end view of an end brush and sleeve in course of assembly in accordance'with my invention;

FIG. 2 is a longitudinal section taken on the line 22 on FIG. 1;

FIG. 3 is a shank end view of my new end brush upon completion of such assembly; and

FIG. 4 is a longitudinal section taken on the line 4-4 on FIG. 3.

Referring now particularly to said drawing, the form of end brush there illustrated to which I apply my novel outer sleeve is disclosed in the aforesaid Benyak Patent 2,449,158, but it will be apparent that the novel brush material restraining sleeve of my invention may similarly be applied to a wide variety of other brushes to serve a like purpose. Theend brush as shown comprises a cup shaped holder 1 which may be of steel or some other metal from the base of which protrudes a short shank or stem 2 adapted to be gripped in an appropriate chuck or collet for mounting in a power driven tool such as conventional hand-held air operated tools adapted to drive the brush at between 8,000 and 10,000 r.p.m. Stem 2, of course, is thus co-axial with the axis of rotation of the tool. A bundle of brush bristle material such as fine wire bristles 3 is passed through an annular sheet metal ring 4 and rebent around the latter so that both ends of the bristles extend in the same direction side by side. This ring with the bristles extending therefrom is now inserted within the cup shaped holder 1 and the lip 5 of such holder compressed to assist in securing the bundle of bristle material therein. The extreme outer edge of such lip may desirably be slightly recurved as shown, and the corresponding edge 6 of the inner ring 4 will desirably be flanged inwardly through transmitted pressure, likewise as shown.

Brushes of the type just described have met with very considerable commercial success, but as noted above, when utilizing very fine wire brush bristle material (eg steel wire having a diameter of .005 inch), it has been found that excessive long fracture of the brush material may result due to hard usage, particularly when the brushes are driven at very high speeds and are handled by unskilled labor.

I may slip a cylindrical or tubular length of a selected synthetic plastic material 7 over the cup shaped holder portion 1 of the assembled brush as shown in FIGS. 1 and 2 or alternatively, and more commonly, I produce such cylinder in situ by wrapping the cup 1 with a number of turns of thin plastic tape. Such plastic is selected for its ability to shrink substantially upon subsequent treatment and also for its ability when thus shrunk to yield in at least a somewhat resilient fashion. A particular suitable plastic for my purpose has proven to be an irradiated polyethylene film commercially available as Irrathene manufactured by Chemical & Metallurgical Division of General Electric Company, Pittsfield, Massachusetts. When a number of turns of such tape have been wrapped on the cup shaped holder as shown in FIG. 2, such tape may be painted with a 10% solution of dicumyl peroxide in xylene. The end of the Irrathene tape may then be secured with a pressure sensitive tape such as Mylar tape (a polymer of ethylene terephthalate). The brush assembly may then be heated in an oven for one-half hour at a temperature of from about to C.

and the heating thereafter continued for another half.

wardly tightly to encircle and embrace the tuft of fine wire bristles 3, forming a protective collar for such bristles. The Irrathene is also a highly desirable material for my purpose inasmuch as it may be obtained in tape from which will shrink substantially only in a direction longitudinally of the tape when treated as above. The treating operation also serves to bond the several layers of tape together into a unitary circumferential guard and collar.

The degree to which the plastic layer 4 extends over the outer surface of the cup shaped holder is not critical, but there should be some degree of overlap as much better results are obtained when this is the case than when a band of the shrunk plastic encircles only the brush bristle material. It is also advantageous to apply the plastic layer to the holder with such layer extending over a portion of the bottom 9 of such holder since this substantially complete covering of the cup presents a smooth outer surface which reduces the likelihood of loosening or tearing off the collar during brush operation under rough conditions.

The extent of the plastic wrap overlying the brush bristle wire is, however, rather important and when using a conventional end brush having a cup diameter of from about /2 inch to inch, it was found desirable for such plastic portion 8 to extend only from about inch to about inch beyond the lip of the cup. Under these circumstances, tearing of the plastic collar is avoided despite the outwardly flaring movement of the brush bristle material in use, and the collar tends itself to curve or flare outwardly sufficiently to provide a resilient vibration damping cushion on a fairly large radius which consequently prevents excessive localized concentration of stress in this region, and the life expectancy of the brush is accordingly much enhanced.

When employing exactly the same type of end brush in the same operations, using relatively unskilled labor, it has been found that the employment of my new plastic collar can be relied upon to extend the useful working life of the brush from two to four times. Needless to say, this represents a very substantial gain far outweighing the cost of the collar. In a typical operation, such brushes using .005 inch steel brush wire are employed to remove the carbon deposit from the tops of the pistons of airplane engines and also removing carbon from the ring grooves and the sides of the pistons. Other aircraft engine parts such as piston pins, small control valves, etc., also require to be cleaned prior to inspection for cracks and other defects. It was found that the relatively short collar described above was not susceptible to tearing 0r excesive roll-back as are sleeves which are too long, and, moreover, such collar permits the brush wire to flare out into a position almost perpendicular to the axis of rotation of the tool in use, this being desired when performing operations of the type described. While an appreciable amount of heat is developed in the brush, this does not appear to have any deleterious effect on the brush or the plastic collar.

Not only is a much increased brush life achieved by employment of my invention, but also danger to the operator is considerably reduced since broken brush wires may be thrown off from ordinary brushes at quite high speeds. As above indicated, the principle of my invention may also be applied to various other brushes such as the cup brushes of Peterson Patent 2,480,877 and the double tufted brushes of Peterson et al. Patent 2,465,396.

Other plastic materials such as rubber may be employed as the collar, being wrapped under tension and secured in this condition by means of cement. The wellknown plastic electricians tape may likewise be employed in a generally similar manner, but neither of these materials is as satisfactory as the irradiated polyethylene tape described above and less uniform results are obtainable. The polyethylene tape which has been irradiated with gamma rays (high speed electrons) which may be derived from Cobalt 60 and certain other radioactive materials, ordinarily themselves rendered radioactive by exposure to radiation from fissionable materials, to render it shrinkable in one direction only is much superior in the results obtainable. While, in the case of the most common sizes of end brushes, the collar will seldom protrude more than A inch beyond the lip of the cup, it will in some cases be desirable to cause the collar to extend approximately one-half the bristle trim length, i.e. one-half the length of the bristles protruding from the cup. The collar flexibly, resiliently and yieldingly resists sharp flexing of the bristles where the latter emerge beyond the lip of the cup and tightly but yieldingly support the bristles. The collar thus permits controlled flaring of the bristles while eliminating sharp bending of the latter where they emerge from the cup. Heavy concentrations of stress in the bristles are accord ingly prevented. While particularly valuable for use with brushes having wire bristles, my new construction is also of value in brushes utilizing other types of bristles including wire of other metals, plastic coated wire, nylon coated glass fiber and tampico fiber, for example. Reference may be had to the co-pending application of Ruben 0. Peterson, Serial No. 660,908, filed May 22, 1957, End Brush Construction, for a preferred type of end brush in conjunction with which my new invention may particularly advantageously be employed.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In a rotary end brush having a cup-shaped metal holder with an integral co-axial stern extending therefrom for mounting and driving the same, a sheet metal cylindrical ring co-axially received entirely within said holder, and a bundle of fine steel wire bristles having a diameter on the order of .005 inch inserted through said ring and doubled back thereabout between said ring and the encircling wall of said holder so that both ends of said bristles extend from said holder to form the brush face, the lip of said cup-shaped holder being inwardly compressed to assist in securing said ring and bristles there in; an irradiated polyethylene film collar encircling said holder and shrink-fitted thereon engaging the underside of such cup and extending beyond said lip of said holder where it tightly embraces said bundle of bristles where they emerge from said holder.

2. The brush of claim 1 wherein the diameter of said holder is from about /2 inch to inch and said collar extends from about /a inch to about A inch beyond the lip of the cup.

3. In a rotary end brush having a cup-shaped holder and a bundle of brush bristles secured therein and extending therefrom; a plastic collar encircling said holder and extending a short distance therebeyond to embrace said bristles where they emerge from such cup, said collar being of reduced diameter where thus embracing said bristles, tightly but yieldingly to support the same, said bristles being of fine steel wire, and an axial stem on said holder adapted to be gripped and held by an appropriate chuck for rotation about such axis.

4. In a rotary brush having a holder and brush bristles extending therefrom in a direction generally parallel to the axis of rotation of said holder; a plastic collar secured on said holder and extending a short distance therebeyond tightly but resiliently yieldingly embracing and supporting said bristles, said collar being of irradiated polyethylene and said bristles of fine steel wire.

5. The brush of claim 3, wherein said bristle wire has a diameter on the order of .005 inch.

6. The brush of claim 3, wherein said plastic collar extends from about 4; inch to about Mr inch beyond the lip of the cup.

5 6 7. The brush of claim 3, wherein said cup shaped 2,421,647 Peterson June 3,1947 holder has a diameter of about inch, said plastic collar 2,495,559 Weiler Jan. 24, 1950 also engages the underside of said holder and extends 2,656,559 Wiseman Oct. 27, 1953 from about inch to about inch beyond the lip of 2,755,496 Benyak July 24, 1956 the cup, and said bristle wire has a diameter on the order 5 FOREIGN PATENTS of .005 inch.

821,782 Germany Nov. 19, 1951 References Cited in the file of this patent OTHER REFERENCES UNITED STATES PATENTS 10 Irrathene (General Electric Technical Report), July 209,279 Marsden Oct. 22, 1878 26, 1956, pages 1 and 10-14.

305,545 Sutton Sept. 23, 1884 

